Can I find someone who died in prison?

Question:

Can I find someone who died in prison?

I'm looking for a relative who died in a (presumably) MO or KS prison within 1960-62. I was told he had mob connections, and possibly had tax-evasion issues. He lived in an area that was rife with mob activity at the time- other relatives that don't get along with his surviving family members had ties to the Civellas. I don't know much about this part of my family, but I know his name, his wife's and his children's names. I know he was probably born around 1915-1923 and he died in prison in about 1961. Supposedly something to do with either taxes, or his mob connections landed him there. Or it could be he molested his daughter. I don't know. Does anyone know how I could find a public record of his incarceration or his death? I can't find the marriage records, even though I know he was married to the mother of his children, and know her name. BUT I was able to find the marriage record of who she married 2 years later. It is all weird. No trace of the guy I'm looking for.

Additional Details

4 days ago
I should have clarified- I have used a PI and they came up empty handed; Except, of course, for my $$. Then I had several memberships to ancestry, and the SSD and could not find a definitive match. He may not have been issued an SSN because he was born in the early 1900's and never served in the military or worked any job that required a pension- apparently (from family lore), he only did under-the table work for political figures with mob ties.

Best Answer - Chosen by Asker: 4 days ago
I should have clarified- I have used a PI and they came up empty handed; Except, of course, for my $$. Then I had several memberships to ancestry, and the SSD and could not find a definitive match. He may not have been issued an SSN because he was born in the early 1900's and never served in the military or worked any job that required a pension- apparently (from family lore), he only did under-the table work for political figures with mob ties.